Tarn
New member
Has anybody any experience of these devices
Thanks Tarn
Thanks Tarn
Sterling Alternator to Battery
- Thread starter Tarn
- Start date
West Coast
Well-known member
Yup, fitted one a couple of years ago. Works really well for me, charging the batteries much faster than before. On my last boat, I had fitted an alternator controller, and this was an option this time, but I preferred the idea of the independent A to B unit. I have a Mastervolt battery monitor so can monitor the charge current and the battery levels reasonably accurately so comparing the performance before and after fitting the A to B unit was interesting!
William_H
Well-known member
I am sure they are OK. Other options and much more efficent would be an alternator controller to increase output voltage in a controlled manner to increase charge rate. The down side being it usually requires modification to the alternator. Or a simpler option is to add more battery capacity which then increases total current charged into battery bank. (giving you more capacity but added weight etc.) ol'will
Bobc
Well-known member
Yes, lots. What do you want to know?
Tell us what setup you have (alternator/splitter/battery banks), and what you're trying to achieve.
Tell us what setup you have (alternator/splitter/battery banks), and what you're trying to achieve.
duncan99210
Well-known member
I’ve got one. Been using it for about 6 years or so now. Simpler to fit than the alternator controller and does what it says on the tin. Also meant I could get rid of the diode splitter which separated the engine and domestics batteries.
pvb
Well-known member
Another advantage of the Sterling A-to-B charger versus an add-on alternator controller is that it delivers a multi-stage charge to the domestic batteries, including the ability to drop to a float voltage.
Lightwave395
Well-known member
The downside is if it goes wrong after 3 years and you try to get help from Sterling - you might get an offer of a small discount on another new one if you're lucky.
Piddy
Active member
I fitted one last winter - no problems fitting or in use.
I had something I didn't understand and called Sterling. The person that answered was helpful and polite.
I had something I didn't understand and called Sterling. The person that answered was helpful and polite.
Tarn
New member
Thanks all for your comments and advice ??
ianc1200
Well-known member
Had one since about 2006 ish. Every so often convinced it's not working, but after replacing all my domestics during the 2019 Trad Rally (wasn't easy...) the alternator to battery worked much better.
Frankklose
Member
I'm in a process to exchange the house batteries to lithium batteries. Will use the Sterling A2B to limit the charge current. As you might Know these Lifepo4 take as much current as they can get, which means they will damage the alternator. I got the 60A version and it supplies from a 50 A Sterling power supply 43 A to the lithium batteries. I have only been able to do bench testing because of Covic1p can't get to the boat. Order the blue 280ah from China and JBD BMS (Overkill BMS). The footprint of the 280ah is the same as the 120A Lead Acid. It gives me 250ah usable energy this compares to a lead acid 500ah.
Also with charging it takes the available 50A out of the charger which is also an older Sterling Charger. Was very afrthat the charger or A2B would be killed, but survived already a few 280Ah charging cycles. Just for info paid 403 Euro for the batteries and 70 Euro for the smart BMS with Bluetooth. Looking forward to install it on the boat.
Also with charging it takes the available 50A out of the charger which is also an older Sterling Charger. Was very afrthat the charger or A2B would be killed, but survived already a few 280Ah charging cycles. Just for info paid 403 Euro for the batteries and 70 Euro for the smart BMS with Bluetooth. Looking forward to install it on the boat.
tawhiri
Member
Yes no problems so far, it puts full charge back into the starter battery for the first 4 minutes then does the four stage charge to the service battery.
Now, after 14 years I still have the same starter battery, so it obviously works.
Now, after 14 years I still have the same starter battery, so it obviously works.
Poey50
Well-known member
I got rid of my Sterling A2B prior to fitting LFP as it doesn't have a suitable charging profile in my view. There is a lithium setting but the bulk voltage is high at, from memory, 14.6v. I looked at using other lead acid profiles with lower target voltage but they all have too long absorption stages. It's true that the temperature sensor on the alternator should help to prevent overheating but I'm not sure how well the unit would survive a BMS generated high voltage disconnect. I know that Sterling don't recommend A2Bs for LFP - it's their B2B that they recommend but many people prefer the Victron Orion TR if they are going the B2B route.
Edit: I've checked the LFP profile.. it is 14.6 target voltage but it reminded me that even worse is the 14.4v float voltage. Most people have no float at all with LFP, just constant current up to the target voltage, maybe a short absorption stage for balancing and then stop. Any float setting above 13.6v is damaging since LFP unlike lead acid will continue to take charge but with a BMS would cause a high voltage disconnect.
Also, do bear in mind that bench testing won't give you much indication of how much charge you will get from the alternator as the limiting factor here will be alternator temperature which will shut off charging via the heat sensor. I think I read something from Rod Collins (Marine How To) on this indicating that the A2B doesn't reduce charge when hot as Balmars do, but just switches off so you get a constant cycling of on / off as the alternator alternately cools and overheats.
Really the best way to go is to charge the LFP direct (not even via a B2B) with a good quality alternator like the Balmar, an external regulator like the Balmar MC614 (or even better, the Wakespeed 500) and a Sterling Alternator Protect as a backstop against high voltage disconnect. That really makes use of the LFPs big advantage of taking all the charge you can throw at it but without causing damage.
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sailinglegend420
Member
On the face of it is a very clever idea to save the cost of having to modify the alternator, or buy a new one, but it is very very inefficient in electrical terms. It just puts a heavy load on the alternator to lower the voltage and sucks as much current as it can and then amplifies the voltage to charge the batteries. This can cause premature failure of an old alternator, so it would be more cost-effective to buy a new one that can be controlled by a cheaper external regulator.
Yes, it works and boosts the voltage, but the in-efficiency must be close to 30%. In previous versions of the publicity material Mr Sterling describes how it turns the main charging off for 3 minutes every 20 - he says to give priority to charging the starter battery. After 20 mins any starter battery will be fully charged, so I suspect this is to allow the alternator to cool down, but Mr sterling has made this a "feature".
3 mins in every 20 means 15% lost, and the high current DC to DC conversion will probably lose another 10-15%, you have a unit that does a job but you have lost 25-30% of any power produced by the alternator.
This is the graph from the old brochure showing the charge voltage dropping every 20 mins. He doesn't use this anymore, I wonder why?
pvb
Well-known member
Had it occurred to you that the product's mode of operation could have been modified? The last time this "feature" was mentioned in any publicity material was 2007, since when I'd expect there to have been enhancements to the unit's software.
And here's the graph they've been using since 2008...
Frankklose
Member
I had the A2D working on the bench, noticed only when I got 72amps out it shut down, when I used less input power like 25Amps it stayed on. This was exactly were I was looking for.
Most of our sailing boats are between 7 and 11m in length, therefore the engine has 10 to 40 horse power. The alternator supplies 35 to 120A. Usable power is between 20 to 70 A. The alternator belt is mostly a 10mm V belt and 120a ist all what can be delivered to alternator. If you more charging power the belt size needs to be bigger 30mm. Look at balmar...most people want to charge there batteries and don't want to change belts, pullies etc. If you want to use a Lithium Batterie you have to limit the charge current to the max what the alternator can deliver continuously. For this you need the Alternator to Battery Charger.
The is some misconception that you need all new charging equipment. This is rubbish...
The Lifepo4 has a very very low internal resistance an can draw more then twice of the battery capacity e.g. 280ah Lithium can easily draw 600a. Therefore the current needs to be limited. The voltage curve is very flat. From 5% to 95% it will draw as much current as it gets. A constant current loader with a max voltage of 14.5 volts is necessary. This is a typical charger for AGM batteries. For the Alternator charging you need a A2B. Don't believe all the marketing rubbish.....there is a lot of information available which is wrong. The law of ohm, ampere and watts has not changed with the technology....
It's very nice to have a battery on board which has 5times the capacity of a lead acid same footprint. Important is a BMS (Battery management system). The BMS makes sure that battery gets not overcharged and too low discharged.
The Sterling A2B is very clever device.
Most of our sailing boats are between 7 and 11m in length, therefore the engine has 10 to 40 horse power. The alternator supplies 35 to 120A. Usable power is between 20 to 70 A. The alternator belt is mostly a 10mm V belt and 120a ist all what can be delivered to alternator. If you more charging power the belt size needs to be bigger 30mm. Look at balmar...most people want to charge there batteries and don't want to change belts, pullies etc. If you want to use a Lithium Batterie you have to limit the charge current to the max what the alternator can deliver continuously. For this you need the Alternator to Battery Charger.
The is some misconception that you need all new charging equipment. This is rubbish...
The Lifepo4 has a very very low internal resistance an can draw more then twice of the battery capacity e.g. 280ah Lithium can easily draw 600a. Therefore the current needs to be limited. The voltage curve is very flat. From 5% to 95% it will draw as much current as it gets. A constant current loader with a max voltage of 14.5 volts is necessary. This is a typical charger for AGM batteries. For the Alternator charging you need a A2B. Don't believe all the marketing rubbish.....there is a lot of information available which is wrong. The law of ohm, ampere and watts has not changed with the technology....
It's very nice to have a battery on board which has 5times the capacity of a lead acid same footprint. Important is a BMS (Battery management system). The BMS makes sure that battery gets not overcharged and too low discharged.
The Sterling A2B is very clever device.
Poey50
Well-known member
You haven't addressed any of the issues I raised for using the A2B with lithium. I wonder why you think both Sterling, who make it, and Rod Collins, author of the most widely quoted paper on the use of LFP on boats, advise against it?
Just to address briefly your statement above that I highlighted in red. Whether the equipment is new or not is irrelevant. What does matter is whether it meets the charging needs of LFP which are distinct without much leeway but, in fact, much simpler than lead acid. Existing chargers must be assessed for suitability and those with the most user-customisable settings are the most useful. Equalisation, high target voltages, long absorption times and any floating above 13.4 volts are all going to cause damage. The Sterling A2B fails on at least two of those whichever setting you use.
Edit: I've checked the Sterling site. If you scroll down this page ... Alternator to Battery Chargers up to 130A ... you will find this warning written in red ...
"NOT RECOMMENDED FOR USE WITH LITHIUM BATTERIES WITHOUT AN EXTERNAL CURRENT LIMITER - The AB system is not a current limiting system and will allow your lithium to draw as much current as it sees available. If you are charging lithium we advise you towards the BB system of chargers. It will provide the correct voltages for lithium, you just need to be aware of the above."
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Frankklose
Member
I am using the 60A A2B and a 90A alternator. If I would use a 130A A2B it would kill the alternator. The A2B will test how much it can draw. Used for testing 12A ,25A, 50A and 75A supplies. Just can not get to the boat at the moment. The old Sterling charger 50A set to AGM, worked fine. There is no float for Lifepo4. Float to lifepo4 is another marytale...
Poey50
Well-known member
The size of the A2B compared to the alternator is a different point. Your use of a 60amp A2B will just cause the same problems I am talking about, only a bit slower, that is all. I think you are saying that float to LFP is a fairytale ... is that correct? Partly I would agree - 13.4 v and below is effectively no float at all - that figure is used to effectively prevent holding LFP at a high state of charge which shortens its life.. So how will you cope with float settings on the A2B that cannot be lowered to 13.4v and below? The lithium profile goes from 14.6v at the end of bulk charging to a 'float' of 14.4 v. So how will you bring charging to an end using the A2B? And if you can't bring it to the end and instead have to rely on your high voltage disconnect on your BMS what do you imaging the resulting high voltage spike will do to your A2B, your alternator diodes, and to your other marine electronics?
I'm going to leave it here as this isn't my thread. I've given you enough clues. I've continued for the benefit of anyone reading over our shoulder to warn them off either now or in the future.
Good luck!
sailinglegend420
Member
Their current brochure uses exactly the same description as to how the unit works.....
"We put a "load" on the alternator to pull the alternator voltage down. This fools the alternator into thinking that there is a major drain on the system and as such, the standard regulator works at full current. However, the voltage is pulled down to a totally useless voltage for charging batteries. So the new system takes in this high current, but low voltage, and amplifies the voltage to charge the auxiliary battery bank at a much higher voltage than the base system voltage."
Aditionally it now has a new 'FEATURE":
2) Alternator temperature sensing: This disengages the unit in the event of the alternator temperature getting too high, it then re-engages the unit when the alternator cools down.
So nothing has changed except that it maybe 'turns off' the alternate for much longer to let it cool down for more than 3 minutes. This not only makes the charging much less efficient but also means it will take much longer.
